Method for switching a sensor system between modes and switchable sensor system

ABSTRACT

A method for operating a sensor system, having at least one capacitive sensor element, which is attachable to the surface of machines or machine parts, electrical field lines on the sensor element changing in the event of an approach and/or a contact of a body or object, and the at least one sensor element being connected to a control unit, which, based on the detected change of the field lines of the at least one sensor element, triggers a safety function on the machine or the machine part. The at least one sensor element has, in addition to fulfilling the safety function, an operating function, which is concluded from the location of the at least one sensor element and the time curve of the change of the field lines, and the safety function has priority over the operating function in a base state of the sensor system.

RELATED APPLICATION INFORMATION

The present application claims priority to and the benefit of Germanpatent application no. 10 2012 211 231.6, which was filed in Germany onJun. 29, 2012, and German patent application no. 10 2012 212 754.2,which was filed in Germany on Jul. 20, 2012, the disclosures of whichare incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a method for operating a sensor systemand a sensor system.

BACKGROUND INFORMATION

A method for operating a sensor system and a sensor system are discussedin DE 10 2009 029 021 A1 of the applicant. It includes at least onecapacitive sensor element, whose field lines generated thereby change inthe event of an approach of a body or object, the change being able tobe detected and analyzed with the aid of a control unit. The knownsensor system is used in particular in handling robots or similarmachines or devices for the purpose of switching the handling deviceinto a safety mode, in the case of which the movement of the affectedmachine component is stopped, in the event of approach of a human or an(unexpected) approach of an object to a moving machine part, forexample, a robot arm. In particular, injuries in the event of acollision of the handling device with a human or damage to objects orthe handling device may thus be avoided or at least minimized. The knownsensor system may include a plurality of planar sensor elements, whichare arranged over the entire surface of the handling device like asensor skin, for example, and are connected to one another by circuitry.

Applications in which handling devices collaborate with humans in ashared workspace will become more and more important in the future. Suchapplications occur, for example, in product manufacturing, for example,in assembly, during welding or lacquering, in the field of so-calledservice robots (for example, for pick-up and delivery services),cleaning robots, inspection robots, in the field of autonomous vehiclesin the environment of humans, in the field of medical robots, which workclosely with humans (for example, for angiography and tumor treatment),or other applications. The collaboration capability of such machines isessentially based on two basic functions, safe movement in theenvironment of humans and intuitive interaction with humans.

With respect to the interaction capability, it is typically implementedusing classical operating elements such as buttons, switches, keyboards,rotating and sliding controllers, joysticks, computer mice, and touchscreens. Speech recognition systems are also known, which react tospoken commands, and also visual systems, which recognize the movementsof an operator (for example, in the form of gestures). In addition,various interaction technologies are known for controlling robots, e.g.,indirect operation via classical operating elements, or directoperation, in the case of which the operator displaces the robot armusing his hands (detection of the operator command by measuring themotor current via the drive regulation or by additional torque sensorsin the joints of the robot arm).

SUMMARY OF THE INVENTION

The present invention is based on the object of providing a method foroperating a sensor system or a sensor system according to thedescriptions herein so that it is suited to be used both as a safetysystem to avoid collisions of machines or machine components with humansor objects, and also as a system for interaction between a machine andan operator.

This object may be achieved in the case of a method for operating asensor system having the features described herein essentially in thatthe sensor element has, in addition to a safety function, an operatingfunction, an operating function is concluded from the location of the atleast one sensor element and the time curve of the change of the fieldlines, and the safety function has priority over the operating functionin a base state of the sensor system. In other words, this means thatthe same sensor element of a sensor system may be used in differentways, as a trigger for a safety function and as a switching element foran operating function. For safety reasons, it is provided that thesafety function has priority over the operating function in a base stateof the sensor system. This means that, for example, no gestures may beexecuted in direct proximity to the moving machine or the moving robot.If an operator attempts this, the safety function will decelerate themachine or the robot safely to a standstill. Only then may the operatorretrieve the desired function using a gesture. In particular injuries topersons and damage to machines or objects are thus reliably.

Advantageous refinements of the method according to the presentinvention for operating a sensor system and a sensor system are setforth in the further descriptions herein. All combinations of at leasttwo features which are disclosed in the claims, the description, and/orthe figures fall within the scope of the present invention. Featuresdisclosed with respect to the method are to be considered to bedisclosed and claimable with respect to the device and featuresdisclosed with respect to the device are simultaneously to be consideredto be disclosed and claimable with respect to the method.

To simplify the operation of a machine or a robot, for example, it maybe provided that the safety function may be temporarily disabled by theoperation of a safety switch. This means that by intentionally pressinga safety switch, the machine or the robot is immediately switched intoan operating mode, in the case of which an approach of a human or anobject to a sensor element is not classified as safety-relevant, sothat, for example, the movement of the machine or the robot is notstopped. In this operating state, the operator assumes responsibilityfor the safe operation of the machine or the robot system. The safetyswitch may be configured in such a way that, when it is not beingoperated or pressed by an operator, it switches back into its originalswitching state, in which the sensor element of the machine or the robotis in its safety mode.

Another advantageous embodiment of the present invention provides thatthe safety function has three different switching states as a functionof the detected distance of a body or an object from the machine or themachine part, that in the first switching state, which is designated asnear range and which is assigned to a short distance (for example, lessthan 20 cm) of the body or object from the machine or the machine part,the movement is completely stopped by the safety function, that in asecond switching state, which is designated as moderate range and whichis assigned to a moderate distance (for example, between 20 cm and 40cm) of the body or object from the machine or the machine part, themovement of the safety function is limited to a safe speed V1, and thatin a third switching state, which is designated as far range and whichis assigned to a long distance (for example, greater than 40 cm) of thebody or object from the machine or the machine part, the movement of thesafety function is limited to a safe speed V2, which may be greater thanspeed V1. The following is meant here: at close range, the safetyfunction ensures a safe stop, so that a hazard for the operator nolonger originates from the movement of the machine or the machine partand the operator may execute arbitrary gestures directly in front of thesensor elements. In the moderate range, only gestures may be executed,in the case of which the hand approaches not closer than up to a minimumdistance of, for example, 20 cm to the moving machine or the machinepart. This switching state may be used for the purpose, for example, ofguiding a robot in a contactless way using a hand, in that the robotregulates its position so that its distance and its orientation to thehand always remain identical. At far range, there is no restriction forthe execution of gestures.

In a simplified embodiment, the moderate range may be omitted, so thatonly a switching threshold of 20 cm exists, for example, which separatesthe near range from the far range.

Another advantageous embodiment of the method according to the presentinvention provides that the operating function has multiple operatingmodes, a first operating mode relating to teaching of a gesture by thesensor system, and a second operating mode relating to execution of agesture, which was taught in the first operating mode, by the machine ora machine part. The first operating mode therefore means, for example,that a specific gesture is repeated multiple times in succession by anoperator, and the sensor system stores the particular sensor valuesdetected during the execution of the gesture. An “average” signal curvefor a specific gesture may be ascertained from the stored sensor values,for example, which, subject to tolerance values, also allows therecognition of gestures which deviate from this “average” gesture, butare obviously to trigger the same function by the control unit. As soonas the teaching process or the first operating mode is completed, thesensor system operates in the second operating mode. If a gesture isexecuted, the control unit thus compares the average signal curves ofstored gestures which are stored in the control unit to the currentlydetected signal curve of a gesture. If a correspondence is found, aspecific gesture is concluded, which has the result that the controlunit of the machine or the robot triggers a specific action, forexample, a screwing process or the like.

A sensor system according to the present invention is distinguished inan advantageous embodiment in that in the operating mode, multiplesensor elements form an operating panel, the input values of the sensorelements, which are detected by the control unit, being able to beanalyzed with the aid of a computer unit.

It particularly may be that when the sensor elements forming anoperating panel represent a subset of all sensor elements situated onthe machine or the machine part, and when the subset of the sensorelements may be selected from the total set of the sensor elements. Thefollowing is meant here: A machine or a machine component is coveredwith a plurality of sensor elements. For example, a matrix of 5×5 sensorelements arranged adjacent to one another forms an operating panel. Thisoperating panel may be configured at an arbitrary point of the machinesurface by an appropriate activation of corresponding sensor elements bythe control unit. This means that, for example, the affected operatingpanel may either be formed on a robot arm, or in the area of a supportelement. With the aid of such an embodiment of the present invention, anoperating panel of the sensor system may be freely adapted to greatlyvarying machines or machine components and also applications, withoutadditional hardware devices having to be affected for this purpose. Theassignment of the sensor elements to the operating panels is performedsolely by software.

According to the exemplary embodiments and/or exemplary methods of thepresent invention, it may be provided that at least one sensor elementin the operating mode acts as a digital switch or as an analog switch,for example, like a slide controller. This means that in the operatingmode, for example, if a specific threshold value is exceeded at thesensor element, the control unit turns a specific machine element on oroff, regardless of the value by which the threshold value was exceeded.Alternatively thereto, however, the absolute level of the detectedmeasured value of the sensor element may also be used for the purpose ofbeing converted into a corresponding speed signal for operating amachine element, for example, so that the level of the sensor signalcorresponds to a specific analog value (for the speed of the machinecomponent).

In order to give an operator feedback as to whether, for example, agesture executed by him was correctly detected or interpreted by thesensor system, it may be provided in another embodiment of the presentinvention that at least one visual, acoustic, or other display elementis provided, with the aid of which the control unit outputs a signal inthe operating mode. For example, this display element may be a monitor,which signals the detected gesture or a specific operator command by acorresponding visual display as feedback to the user. Alternativelythereto, for example, it may be communicated to the operator by anacoustic signal that the control unit has unambiguously recognized aspecific gesture or also if a gesture was not recognized. Other types ofelements, for example, LEDs, may also be used for such feedback for theoperator.

In addition, it particularly may be that if the at least one sensorelement acting in the operating mode is visually marked on the machineor the machine component. It is thus signaled to the operator at whichpoint he is to execute a gesture, for example, so that it may berecognized as easily and unambiguously as possible by the sensor system.It is conceivable, for example, to perform such a marking with the aidof a light, which is only recognizable in the operating mode of themachine. However, printed markings or the like may also be used, so thatthe operator recognizes the area of the sensor elements via which aninput of gestures is made possible, for example.

Further advantages, features, and details of the exemplary embodimentsand/or exemplary methods of the present invention result from thefollowing description of exemplary embodiments and on the basis of thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic view of a handling robot during the transfer ofan object by an operator.

FIG. 2 shows the fundamental structure of an interaction system, inwhich an operating panel constructed from 24 sensor elements is used torecognize a gesture.

FIG. 3 shows a view to illustrate an exemplary mode of operation of avirtual operating element for detecting a keypress.

DETAILED DESCRIPTION

Identical elements or elements having an identical function are providedwith identical reference numerals in the figures.

FIG. 1 shows a machine in the form of a handling robot 100. Handlingrobot 100 includes a machine base 101, which carries a robot arm 103,which is rotatably mounted in a first axis 102. Robot arm 103 has threearm sections 104 through 106, which are in turn each mounted so they arepivotable in one axis 107 through 109 in the direction of the doublearrows shown. Arm section 106 carries a gripping mechanism 110 forgripping an object 1. Such a handling robot 100 thus described is suitedfor the purpose of receiving object 1 within the range of robot arm 103at an arbitrary location and delivering it at a second, also arbitrarylocation.

At least areas of handling robot 100 are covered by a sensor skin (notshown in detail) having sensor elements 10, which are each configured ascapacitive sensor elements 10. Sensor elements 10 form a sensor system.Sensor elements 10 may each be configured identically; however, they mayalso be configured differently or have different sizes. With respect toa fundamental construction of such a sensor element, reference is madeto DE 10 2009 029 021 A1 of the applicant, which is thus to be part ofthis application.

Sensor elements 10 are connected to a control unit 20 of handling robot100. In control unit 20 of handling robot 100, the particular locationsof sensor elements 10 on handling robot 100 are stored. For example,some of sensor elements 10 are used according to the present inventionin such a way that the control of a function or an operation of handlingrobot 100 may be performed via these sensor elements. For this purpose,multiple virtual operating panels 11 through 14 are generated on thesurface of handling robot 100, sensor elements 10 assigned to individualoperating panels 11 through 14 being freely assignable as a subset toall of sensor elements 10 situated on handling robot 100 via an inputunit (not shown), for example. Operating panels 11 through 14 describedhereafter are only to represent possible variants, the number andconfiguration of which are variable to a high degree.

First operating panel 11 is situated in the area of third arm section106 of robot arm 103 on a lateral surface and acts as a digitalswitching element, so that if the hand of an operator 30 approaches, forexample, gripping unit 110 is opened or closed. Operating panel 12 issituated on second arm section 105 of robot arm 103 and includes sixsensor elements 10, for example, which are used for the sequence controlof the operation of handling robot 100, so that if the hand of operator30 approaches a specific sensor element 10 in operating panel 12 ofhandling robot 100, for example, a stored operating program starts or isexecuted. Operating panel 13 is situated on first arm section 104 ofrobot arm 103 and is used as a virtual proximity surface for guidingrobot arm 103. In particular, if an identical operating panel 13 issituated on the opposite side of first arm section 104 on robot arm 103,which is parallel to the plane of the drawing of FIG. 1, robot arm 103may be caused to rotate in first axis 102 in the desired direction, inorder to teach a specific movement sequence of robot arm 103, by theapproach of the hand to one or the other operating panel 13. Finally, anoperating panel 14 is situated on machine base 101, which is used fordata input in the form of a virtual keyboard, and includes a pluralityof sensor elements 10 situated adjacently to one another and one overanother.

To make operating panels 11 through 14 identifiable for operator 30, itmay be provided that operating panels 11 through 14 are emphasized byappropriate markings or visual aids.

Sensor elements 10 shown in FIG. 1 in operating panels 11 through 14 areused, like sensor elements 10 (not shown in FIG. 1) distributed over thesurface of handling robot 100, which are not situated in operatingpanels 11 through 14, for stopping the movement of handling robot 100during the operation of handling robot 100 in the so-called safety modein the event of an imminent collision of handling robot 100 with a humanor an object, in order to prevent injuries or damage. For this purpose,control unit 20 analyzes the input signals generated by individualsensor elements 10. In addition to the safety-relevant function ofsensor elements 10, they are used, as explained above, in operatingpanels 11 through 14 for the purpose of interacting with operator 30(operating mode).

The safety mode has priority over the operating mode. This means that,for example, if operator 30 approaches handling robot 100, which isrecognized by sensor elements 10, initially the speed of robot arm 103is throttled to a safe value, so that contact with moving robot arm 103is precluded. Sensor elements 10 situated within operating panels 11through 14 are then ready to recognize gestures of operator 30. If therobot receives a command at any time to move toward an object or ahuman, to fall below the preset safety distance, or to exceed themaximum speed corresponding to the distance, the execution of thecommand is prevented by the priority of the safety mode.

Manually pressing an optional safety switch 15, which is connected tocontrol unit 20 of handling robot 100, by operator 30 causes theapproach of a human or an object to be classified as notsafety-relevant, while the recognition of gestures is still active. Inthis operating state, the operator assumes responsibility for the safeoperation of the robot system.

As long as safety switch 15 is pressed, control unit 20 of handlingrobot 100 or its sensor elements 10 switch from the safety mode into theoperating mode, in the case of which in particular sensor elements 10situated within operating panels 11 through 14 are used to recognizegestures of operator 30 or inputs. It may also be provided that in theevent of an approach of operator 30 to sensor elements 10, control unit20 initially switches into a mode in which sensor elements 10 in thearea of operating panels 11 through 14 are used to recognize gestures,for example, while the movement of handling robot 100 is simultaneouslyperformed at reduced speed in comparison to normal operation. Uponfurther approach of operator 30 to sensor elements 10, in the case ofwhich the distance falls below a specific minimum distance of, forexample, 10 cm, control unit 20 switches handling robot 100 over intothe safety mode, during which any movement of handling robot 100 or itsrobot arm 103 is stopped.

In order to provide operator 30 with feedback about inputs made by handvia operating panels 11 through 14, a visual, acoustic, or other displayunit 16 may be provided, which receives a corresponding signal fromcontrol unit 20 if, for example, a specific gesture of operator 30 wascorrectly recognized (or was not recognized at all), or if, for example,a gesture is to be repeated.

FIG. 2 shows an operating panel 18, including 24 sensor elements 10.Sensor elements 10 are situated in the form of a 4×6 matrix in operatingpanel 18 and are connected to a central unit 19, which is part of acomputer unit. Operating panel 18 thus formed detects the gestures ofoperator 30. For this purpose, each of sensor elements 10 delivers ameasured value D_(i), which varies with the distance of the finger ofoperator 30 from particular sensor element 10. Central unit 19 takesover the cyclic request and processing of measured values D_(i) of allsensor elements 10 and also the output thereof via an interface. Acontrol computer 25 having an integrated software interaction module 27,which is connected to central unit 19, reads in measured values D_(i) ofall sensor elements 10 as a time series and analyzes them in thefollowing way, as an example:

preprocessing of measured values D_(i)

recognition of taught patterns in the data, for example, with the aid ofcorrelation functions

classification of the patterns according to operating elements andgestures

assignment of the recognized gestures to commands, and

command execution in step 28 (for example, by retrieval of functions,output of signals).

FIG. 3 shows an example of the mode of operation of a virtual operatingelement having six sensor elements 10 arranged adjacent to one another.In this case, the operating element is used to detect a keypress. Theindex finger of an operator 30 is guided in the X direction of the arrowshown. The diagram shown below six sensor elements 10 schematicallyshows the measured value curve of all six sensor elements 10, as afunction of the X position of the finger. Each sensor element 10 has acharacteristic curve similar to a Gaussian curve, the Gaussian curves ofadjacent sensor elements 10 typically overlapping. The X position of thefinger of operator 30 may be derived from six measured values D₁ throughD₆ with the aid of interpolation functions. The resolution of the fingerposition is not linked to the width of sensor element 10 or the width ofthe finger. If adjacent sensor elements 10 are provided, differentfinger positions may also be detected within a sensor element 10 byinterpolation. This measurement principle is transferred to flatlysituated sensor elements 10, in order to detect the finger position inboth spatial directions (i.e., in parallel and perpendicularly to theplane of the drawing of FIG. 3). In a similar way, the distance of thefinger of operator 30 may also be detected on the basis ofcharacteristic sensor data, so that the spatial position of the fingerof operator 30 may be ascertained.

If gestures are to be recognized with the aid of sensor elements 10,these gestures are transformed as a result of the input signals ofsensor elements 10 into a chronological sequence of sensor data. Onetask of control computer 25 shown in FIG. 2 is to take over the backtransformation, i.e., to recognize gestures in the chronologicalsequence of sensor data. Furthermore, module 27 situated in controlcomputer 25 has the two operating modes “configure” and “execute.” Inthe operating mode “configure,” the virtual operating elements(operating panels 11 through 14) are configured by an operator 30 beforehandling robot 10 is put into operation. This is carried out in thefollowing steps, for example:

a. Visualization of the operating elements (operating panels 11 through14) on the surface of handling robot 100, for example, by stickers or inthe form of LEDs delimiting operating panels 11 through 14.

b. “Demonstration” of the gesture at the operating element by operator30. The gesture is stored as a chronological sequence of characteristicsensor data. Permissible variations of the gesture are subsequently alsodemonstrated.

c. Teaching of the gesture: The stored sensor data are reduced tocharacteristic features. A teachable classifier is trained using thesefeatures. The classifier is multiclass capable, i.e., it may recognizeall taught gestures again and assign them separately. In the case ofanalog gestures, it is capable of determining the analog value of thegesture (for example, the distance between the hand of an operator 30and a sensor element 10).

d. Linking the gestures to functions: Operator 30 assigns each taughtgesture to a function or a sequence of functions, which is to beautomatically executed upon recognition of the gesture. For example,this may be a function sequence on control computer 25 or a commandwhich is transmitted via a communication interface to peripheral units.

In the operating mode “execute”, the measured values of sensor elements10 are continuously cyclically read in and the characteristic featuresare calculated. The previously taught classifier continually checkswhether a taught gesture was executed. If so, control unit 20 triggersthe execution of the function linked thereto.

The method thus described for operating the sensor system includingsensors 10 may be altered or modified in manifold ways, withoutdeviating from the exemplary embodiments and/or exemplary methods of thepresent invention. In particular, the use of such a sensor system is notnecessarily restricted to the use in handling robots 100, but rather mayalso be applied in the case of other machines or machine components.

What is claimed is:
 1. A method for operating a sensor system, thesensor system including at least one capacitive sensor element which isattachable to a surface of a machine, the method comprising: receiving,by a control unit from each respective at least one capacitive sensorelement in the sensor system, sensor values reflecting changes inelectrical field lines at the respective sensor element based on atleast one of an approach and a contact of one of a body and an objectwith the machine; analyzing, by the control unit, the received sensorvalues; triggering, by the control unit, a safety function of themachine if the control unit determines, based on the analysis, thesafety function is warranted; using the received sensor values for anoperating function of the machine, wherein the control unit usesreceived sensor values from the at least one sensor element both fortriggering the safety function of the machine and for the operatingfunction of the machine so that the at least one sensor element alsohas, in addition to the safety function, an operating function, whereinthe control unit responds to the received sensor values in a first waywhen the control unit is triggering the safety function, and in a secondway, different from the first way, when the control unit is using thereceived sensor values for the control function; wherein the controlunit determines the operating function based on a location of the atleast one sensor element and a time curve of the changes in the fieldlines, and wherein the control unit prioritizes the functions of themachine and, in a base state of the sensor system, the safety functionhas priority over the operating function.
 2. The method of claim 1,further comprising: disabling, by an operation of a safety switch, thesafety function for a temporary time period.
 3. The method of claim 2,further comprising: automatically triggering, by the control unit andbased on the disabling of the safety switch, the operating function ofthe machine.
 4. The method of claim 1, wherein: the safety function ofthe at least one sensor element has at least two different switchingstates, and wherein each one of the at least two different switchingstates is (i) selected as a function of a detected distance of one ofthe body and the object from the machine and (ii) assigned to a distancerange, for each one of the at least two different switching states, thesafety function safely limits a maximum speed of the machine, and thecontrol unit is configured to trigger the operating function at a sametime as the safety function.
 5. The method of claim 4, wherein: thesafety function of the at least one sensor element has at least threedifferent switching states, and wherein each one of the at least threedifferent switching states is: (i) selected as a function of a detecteddistance of one of the body and the object from the machine and (ii)assigned to a distance range, and for two of the at least threedifferent switching states, the safety function safely limits a maximumspeed of the machine and for a third one of the at least three differentswitching states, the safety function completely stops the machine. 6.The method of claim 4, wherein in a first one of the at least twodifferent switching states the maximum speed of the machine is limitedto a first value and in a second one of the at least two differentswitching states the maximum speed is limited to a second value that ishigher than the first value.
 7. The method of claim 6, wherein the firstone of the at least two different switching states is associated withwhen the detected distance falls within a first range from the machineand the second one of the at least two different switching states isassociated when the detected distance falls within a second range fromthe machine, the second range being greater than and outside of thefirst range.
 8. The method of claim 1, wherein the operating functionhas multiple operating modes including at least: a first operating mode,wherein during the first operating mode the sensor system is taught agesture by storing sensor values during an execution of the gesture byan operator, and a second operating mode, wherein during the secondoperating mode the machine executes an action associated with thegesture.
 9. The method of claim 8, wherein when the operating functionis in the second operating mode, the control unit: compiles the receivedsensor value from each of the at least one sensor element, compares thecompiled sensor values to an average signal curve having an associatedstored gesture, and when the comparison indicates a match between thecompiled sensor values and the average signal curve, executes the actionassociated with the associated stored gesture.
 10. The method of claim1, wherein the operating function of the machine is one of: (i) to gripand release the object, (ii) to implement a sequence of tasks, (iii) toestablish a movement to guide an extendable portion of the machine, and(iv) to engage in a preset movement based on ad hoc commands.
 11. Themethod of claim 10, wherein the operating function being one of (i) to(iv) is inferred from the location of the at least one sensor element onthe machine including a first arm section, a second arm section, a thirdarm section, and a base section.
 12. The method of claim 10, whereinwhen the operating function is: (i) to one of grip and release theobject, the sensor value is used in a first way to identify a user and aproximity of the user to a portion of the machine configured to grip andrelease the object, (ii) to implement the sequence of tasks, the sensorvalue is used in a second way to determine the sequence based on aselection of one sensor element associated with a particular task fromamong the tasks that are assigned to each at least one sensor element,(iii) to establish the movement to guide the extendable portion of themachine, the sensor value is used in a third way to teach a gestureassociated with the movement by contributing towards a signal curve forthe gesture, and (iv) to engage in the preset movement based on ad hoccommands, the sensor value is used in a fourth way to receive data inputassociated with the ad hoc commands.
 13. The method of claim 10, whereinwhen the operating function is to establish the movement to guide theextendable portion of the machine, the control unit uses the sensorvalue to teach a gesture associated with the movement by contributingtowards a signal curve for the gesture, and the control unit compiles anaverage signal curve from the signal curve from each of the at least onesensor element.
 14. The method of claim 1, wherein when the control unittriggers the safety function, the machine is one of decelerated and heldat a standstill.
 15. A sensor system, comprising: at least onecapacitive sensor element attachable to a surface of a machine andconnected to a control unit, each respective at least one sensoroutputting sensor values; wherein the control unit is configured to:receive the sensor values; switch the machine between a safety mode andan operating mode based on the sensor values, wherein the control unituses the received sensor values from the at least one sensor element forboth the safety mode and the operating mode so that the at least onesensor element has, in addition to a safety function, an operatingfunction; wherein the control unit responds to the received sensorvalues in a first way when the control unit is using the received sensorvalues in the safety mode, and in a second way, different from the firstway, when the control unit is using the received sensor values in theoperating mode; and wherein during a base setting, switch the machineinto the safety mode.
 16. The sensor system of claim 15, wherein, whenthe control unit switches the machine into the operating mode, thecontrol unit activates multiple sensor elements from the at least onesensor element that are in a formation on an operating panel to eachgenerate respective sensor values based on detected changes inelectrical field lines, and the control unit, based on an analysis ofthe sensor values from each of the activated multiple sensor elements,recognizes a gesture.
 17. The sensor system of claim 16, wherein themultiple sensor elements in the formation on the operating panel are asubset of all sensor elements situated on the machine, and wherein thesubset of the sensor elements is formed from the total set of the sensorelements by assignment.
 18. The sensor system of claim 15, wherein,during the operating mode, the sensor values from the at least onesensor element are used by the control unit to at least one of: switchan element of the machine one of on or off and convert the sensor valuesto a corresponding analog signal.
 19. The sensor system of claim 15,further comprising: at least one visual, acoustic, or other display unitcommunicatively coupled to the control unit, the display unit outputtinga signal from the control unit in the operating mode.
 20. The sensorsystem of claim 15, wherein the at least one sensor element acting inthe operating mode is identifiable by a visual marking on the machine.